1. Field of Endeavor
The present invention relates to the field of gas turbine technology, and to a rotor blade for a gas turbine.
2. Brief Description of the Related Art
Uncooled, hollow turbine rotor blades are customarily cast from one material. It is also known (U.S. Pat. No. 6,331,217), however, to join large rotor blades of a gas turbine, which are formed of a plurality of separately cast blade sections, by liquid phase bonding. In this case, either the blade airfoil is split in the longitudinal direction of the blade (FIG. 3 of U.S. Pat. No. 6,331,217), or the entire blade airfoil is produced separately from the platform and the blade root (FIG. 6 of U.S. Pat. No. 6,331,217). In the case of large blades, despite the division, this leads directly to large cast pieces having to be produced for the blade airfoil and interconnected in a form-fitting manner.
The same also applies to the rotor blade which is described in US-A1-2006/0120869, which inside the blade has a spar (12) which extends in the longitudinal direction and which in the region of the blade airfoil is enclosed on the outside by an aerodynamically effective shell (48). A similar concept, in which the outer shell is prestressed with a compressive stress, is known from U.S. Pat. No. 4,473,336. Finally, a comparable configuration, in which the outer shell of the blade airfoil is formed of a ceramic, is known from U.S. Pat. No. 4,563,128.
With the increase of efficiencies and effectiveness of modern gas turbine plants, the dimensions of the individual components, and consequently of the rotor blades, are also increased. As a result, considerable weight-related problems, inter alia, can occur in operation, and also manufacturing-engineering difficulties can occur when casting large components.